Based on what they’ve experienced over the years, California residents might suspect that wildfires have become more extreme in a warmer, more drought-prone climate.
A new paper in the journal Science puts that sentiment to the test, with surprising results: California fires spread almost four times faster in 2020 than in 2001.
The study, authored by scientists from the University of Colorado, UC Merced and UCLA, also found that in the West, fires grew 250% faster in 2020 than in 2001 .
“People are pretty good at putting out all fires,” said Park Williams, a UCLA professor and co-author of the study, but “the faster the fire, the more easily it can get out of control.”
Although intuitive, the relationship between the speed at which a fire spreads and the damage it causes to structures and soils was difficult to quantify until recent developments in satellite technology, he said.
Now scientists can plot “trends in daily growth rates,” he said. Using daily images of fire spread for some 60,000 fires from 2001 to 2020, they were able to determine a relationship between damage and speed, Williams said.
“Over this 20-year study period, fires in the United States actually began to spread faster on average,” he said. The 3% of fires with the fastest daily growth rates accounted for about 90% of property losses over the two decades studied.
“In California, more than most other places in the United States, people are confronting changes in fire behavior,” Williams said.
Many Californians live near flammable vegetation and are increasingly exposed to danger.
The study gave several possible explanations for the increase in firing speed.
“Fires could grow more quickly due to warming trends, vegetation transitions to more flammable fuels, or the co-occurrence of high winds with an increase in human-caused fires,” the study suggests.
The recent wildfires in California have caused death and destruction and brought the homeowners insurance industry to the brink of crisis. With fire season ending in 2024, all eyes will be on next year.
